Display device

ABSTRACT

In a display device, wiring for the respective display elements is simplified so that the assembling work and the maintenance work become easy. A large number of display units ( 50 ) are arranged in length and breadth directions to form the display device. Each display unit comprises a display element ( 10 ) comprised of a light bulb, a regulator ( 51 ) comprised of a relay, a non-volatile memory ( 52 ) comprised of an EEPROM and a controller ( 53 ) including a CPU. For these display units ( 50 ), a passage ( 61 ) for power supply and a passage ( 71 ) for supply of synchronizing signal are drawn. Display information to designate change of display mode in time of light emitting or non-light emitting (ON/OFF) state are stored in memories within the respective display units. The controllers of the respective display units carry out ON/OFF control of regulators on the basis of the display information in synchronism with the synchronizing signal to turn ON or OFF the display elements. If a rewrite signal is delivered to the signal transmission passage, the contents of the respective memories can be also rewritten.

TECHNICAL FIELD

The present invention relates to a display device, especially to a typeof display which is attached on a wall, such as an electric bulletinboard, an advertisement sign board or the like.

BACKGROUND ART

Wall display devices, such as electric bulletin boards and advertisementsign boards, are widely used as means for providing information to manyand unspecific people on streets. Such a wall display device usuallyincludes a number of display elements arranged on a plane in which anindividual element is used for one pixel. The respective displayelements are electrically actuated in various manner to displayinformation. In an electric bulletin board, for example, one light bulbis used as one display element for one pixel, and a plurality of lightbulbs are arranged in matrix. By illuminating those of the light bulbsin specified positions, it is possible to display letters and pictures.Recently electric bulletin boards using light emitting diodes in placeof the light bulbs are widely used.

An advertisement sign board uses “panel display elements” as displayelements constituting respective pixels. The “panel display elements”are not light emitting themselves but have a plurality of display facesonly one of which is actually displayed. Usually one of the displayfaces to be displayed can be selected by using a rotary mechanism, suchas a motor or the like. One display face is selected for each pixel,whereby letters or pictures can be displayed.

The display elements for respective pixels, which are thus provided bylight bulbs, light emitting diodes, panel display elements or the like,are electrically actuated. The light bulbs and the light emittingdiodes, for example, can be switched between their light emitting stateand non-light emitting state by On/Off control of electric power supply.By conducting the On/Off control on the respective light bulbs or therespective light emitting diodes providing the respective pixels, onlyrequired pixels can be selectively illuminated, whereby requiredinformation can be displayed. In the panel display elements the On/Offcontrol of electric power supply to the motor is conducted, wherebythose of the display faces to be actually displayed can be selected. TheOn/Off control is conducted on the respective panel display elementsproviding the respective pixels, whereby a required display face foreach pixel can be displayed and required information can be displayed.

In the above-described display devices, needless to say, larger numbersof pixels are necessary for improvement of their display resolution.Accordingly it is necessary that a large number of display elements forrespective pixels are arranged in a matrix. As described above, sincedisplay manners of the respective display elements must be controlled byelectric power supply, it is needed to provide an individual electricpower supply line for the individual display elements. In an electricbulletin board having 100 light bulbs arranged in a matrix, for example,two electric power supply lines are needed for each of the 100 lightbulbs, and therefore totally 200 lines must be wired from a switchboardto the light bulbs. For high resolution a lager number of light bulbsmust be arranged, which increases a number of wiring lines. When anumber of wiring lines becomes increased, a structure of a displaydevice becomes complicated, which need much labor for its manufactureand maintenance. This results in higher manufacturing costs andmaintenance costs.

A display device for solving such problems is disclosed in theInternational Application No. PCT/JP95/00901 based on the PatentCooperation Treaty. In this display device, addresses are defined forevery respective display elements and an addressed signal is deliveredto a common signal line to thereby independently control the respectivedisplay elements thus to simplify wiring. This invention proposes adifferent technique for simplifying wiring for the respective displayelements to facilitate the assembling work and the maintenance work.

DISCLOSURE OF INVENTION

(1) The first feature of the present invention resides in a displaydevice including plural display elements which are arranged in a matrixand have a function to vary display mode corresponding to one pixel bysupplying an electric power, the display device comprising:

a plurality of display units each including a display element, aregulator for controlling electric power supply to the display element,memory means for storing display information to instruct the displayelement to change display mode in time and a controller for controllingthe regulator on the basis of the display information stored in thememory means;

a device casing for accommodating and fixing the plurality of displayunits so that the respective display elements are arranged on apredetermined display screen in a manner adjacent to each other;

an electric power source for producing electric power which is suppliedto the display elements; and

electric power transmission means for delivering electric power producedin the electric power source to the regulators within the respectivedisplay units, in the state where the respective display units areaccommodated within the device casing.

(2) The second feature of the present invention resides in a displaydevice having the first feature:

wherein plural display elements are respectively provided within each ofthe display units; and

wherein display information for the respective plural display elementsare stored in the memory means.

(3) The third feature of the present invention resides in a displaydevice having the first or second feature:

wherein one display element is constituted by three color presentationelements of a first color presentation element for presenting firstprimary color R by supplying electric power, a second color presentationelement for presenting second primary color G by supplying electricpower and a third color presentation element for presenting third colorB by supplying electric power.

(4) The fourth feature of the present invention resides in a displaydevice having the first to third feature:

wherein there are further provided;

a central control device for generating a predetermined synchronizingsignal delivered to the respective display units; and

signal transmission means for delivering the synchronizing signalgenerated in the central control device to the controllers within therespective display units;

wherein the respective controllers have a function to control theregulators at timings synchronized with the synchronizing signaldelivered thereto.

(5) The fifth feature of the present invention resides in a displaydevice having the first to third feature:

wherein there are further provide;

a central control device for generating a predetermined write signaldelivered to the respective display units; and

signal transmission means for delivering the write signal generated inthe central control device to the controllers within the respectivedisplay units;

wherein the respective controllers have a function to carry out rewriteoperation of display information stored in the memory means on the basisof the write signal delivered thereto.

(6) The sixth feature of the present invention resides in a displaydevice having the fifth feature:

wherein unique address information for the respective display units arestored in the respective memory means;

wherein the write signal comprises address information indicating aspecific display unit and display information to be newly written intothe memory means within said specific display unit; and

wherein the respective controllers have a function to replace displayinformation stored in the memory means by display information within thewrite signal when address information stored in the memory means andaddress information within the write signal correspond to each other.

(7) The seventh feature of the present invention resides in a displaydevice having the first to third feature:

wherein there are further provided;

a central control device for generating a predetermined write signaldelivered to the respective display units; and

signal transmission means for delivering the write signal generated inthe central control device to the controllers within the respectivedisplay units;

wherein control programs are respectively stored in the memory means ofthe display units to allow the controllers to be operative by makingreference to the control programs; and

wherein the respective controllers have a function to rewrite thecontrol program stored in the memory means on the basis of the writesignal delivered thereto.

(8) The eighth feature of the present invention resides in a displaydevice having the seventh feature:

wherein unique address information for the respective display units arestored in the respective memory means;

wherein the write signal comprises address information indicating aspecific display unit and control program to be newly written into thememory means within said specific display unit; and

wherein the respective controllers have a function to replace controlprogram stored in the memory means by control program within the writesignal when address information stored in the memory means and addressinformation within the write signal correspond to each other.

(9) The ninth feature of the present invention resides in a displaydevice having the fourth to eighth feature:

wherein electric power transmission means and signal transmission meansare constituted by a same conductive wire to supply electric powerthrough the conductive wire and to superimpose a component of a signalon voltage of the electric power so that said signal is also transmittedthrough said conductive wire.

(10) The tenth feature of the present invention resides in a displaydevice having the first to ninth feature:

wherein a signal to be transmitted by the signal transmission means iscompressed or encoded in the central control device and the compressedor encoded signal is expanded or decoded within the controller.

(11) The eleventh feature of the present invention resides in a displaydevice having the second to tenth feature:

wherein the controller carries out thinning processing or interpolationprocessing with respect to display information stored in the memorymeans.

A display device according to this invention is constituted by providingan array of plural display units within a device casing. Each displayunit includes at least one display element (which carries out display asa pixel), a regulator for controlling supply state of electric powerwith respect to this display element, a memory, and a controller. Forexample, the display element is constituted by a light bulb and theregulator is constituted by a relay provided on an electric powertransmission passage to the above-mentioned light bulb. In this example,the controller controls the relay to switch the light emitting on or offof the light bulb. Instructions (commands) for the controller are storedas display information in the memory. This display information isinformation for instructing the respective display elements to changethe display mode along time axis. In the above-described example whereeach display element is constituted by the light bulb and the lightemitting or non-light emitting state of this light bulb is switched, itis sufficient to prepare display information of the light emitting ornon-light emitting (ON/OFF) state for every unit time which isrepresented by data of one bit. Assuming that the unit time is onesecond, a bit data of logic “1” indicates light emitting (ON) state anda bit data of logic “0” indicates non-light emitting (OFF) state,display information of 8 bits expressed as “10100111” in the memoryinstructs the light bulb to carry out such an operation that it isturned ON for 1 sec., is turned OFF for 1 sec., is turned ON for 1 sec.,is turned OFF for 2 sec., and is turned ON for 3 sec.

The feature of the display device according to this invention resides inthat individual display units respectively include display informationdesignating (indicating) own display operations as stated above, and therespective display units thus independently carry out displayoperations. When only electric power is supplied to the device, it canoperate even if no instruction (command) is given from the external.Accordingly, if power supply is carried out by way of the common powertransmission passage, the respective display units can start independentdisplay operations without giving any signal from the external. In otherwords, in the display device according to this invention, sinceindividual display units have intelligence function, if power supply iscarried out with respect to all display units, predetermined displayoperations can be made. When the common power transmission passage isused, even if the number of display units is increased, necessary numberof wirings is invariant, so the entire wiring extremely becomessimplified. In addition, since the respective display units areoperative on the basis of display information respectively stored in thememories, if predetermined display information are stored in advance inthe memories of the respective display units, it is possible to freelyset desired display operations.

If plural display units are arranged in longitudinal and lateraldirections to constitute a display screen composed of a large number ofpixels with respective one display element being as one pixel, it ispossible to display arbitrary picture (picture image) on this displayscreen. Particularly, if display elements corresponding to three primarycolors of R, G and B are used, it is possible to form color displayscreen. Moreover, if a synchronizing signal generated at the centralcontrol device is delivered to respective controllers within therespective display units, timings at which display modes of pluraldisplay units change can be synchronized with each other. Alternatively,if a predetermined write signal is delivered in place of thesynchronizing signal to rewrite the contents of the memories within therespective display units on the basis of information included in thewrite signal, it is possible to display any picture on demands. It is tobe noted that when addresses are defined for respective display units,it becomes possible to deliver a specific write signal only to anaddressed specific display unit even if a common signal transmissionpassage is used.

Further, if a control program for the controller is stored in thememory, change of the operation can be flexibly carried out by rewritingthe control program. In addition, if the controller is caused to havearithmetic processing function, it can execute compression or expansionof data, encode or decode thereof and thinning processing orinterpolation processing of pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing the configuration of a conventionaltypical electric bulletin board.

FIG. 2 is a front view showing the configuration of a display deviceaccording to the fundamental embodiment of this invention.

FIG. 3 is a circuit diagram of each display unit 50 used in the electricbulletin board shown in FIG. 2.

FIG. 4 is a Table showing display information stored in memory 52 of thedisplay unit 50 shown in FIG. 3 and the state of light bulbcorresponding thereto.

FIG. 5 is a front view showing the configuration of an embodiment inwhich central control device 70 and signal transmission passage 71 areadded to the fundamental embodiment shown in FIG. 2.

FIG. 6 is a circuit diagram of each display unit 50 used in the electricbulletin board shown in FIG. 5.

FIG. 7 is a view showing one example of format of write signal deliveredfrom the central control device 70 in the device shown in FIG. 5.

FIG. 8 is a circuit diagram of an embodiment in which plural signaltransmission passages for connecting the central control device andrespective display units are provided.

FIG. 9 is a circuit diagram of display unit 80 having display functionof R, G, B three primary colors.

FIG. 10 is a partial front view showing the configuration of colordisplay 100 of a structure in which the display units 80 shown in FIG. 9are arranged.

FIG. 11 is a block diagram showing a drive system of a conventionaltypical color display.

FIG. 12 is a block diagram showing an embodiment in which color displayis constituted by using the display device according to this invention.

BEST MODE FOR CARRYING OUT THE INVENTION

§0. Conventional Electric Bulletin Board

The present invention will be explained based on an embodiment shown indrawings attached hereto. First, for comparison of the conventionalelectric bulletin board with the present invention, the structure of theconventional, general electric bulletin board will be explained withreference to FIG. 1. In the conventional electric bulletin board,respective display elements 10 are provided by light bulbs. In thisexample, display elements 10 are arranged in a five by ten matrix andhoused in a device casing 20. A switchboard 30 is provided for supplyingelectric power to these fifty display elements (light bulbs) 10, andcentral control device 40 is provided for giving commands to theswitchboard 30. Two electric power supply lines 31 are wired to each ofthe display elements 10 (only a part of the wiring is shown to simplifythe drawing). The central control device 40 gives to the switchboard 30commands as to which display elements 10 are to be electricallyactivated, based on the information to be displayed (e.g., letters) onthis electric bulletin board. Based on the commands, the switchboard 30supplies electric power to only those of the electric power supply lines31 associated with the required display elements 10. Only requireddisplay elements 10 are thus lit, and information is displayed by usingthe respective display elements 10 as individual pixels.

As described above, such a conventional electric bulletin board,however, has the problem that the wiring is very complicated. In theexample of FIG. 1, two electric power supply lines are necessary foreach of the fifty display elements 10, and therefore totally a hundredelectric power supply lines have to be wired. In practical purposes,high resolutions are necessary to display complicated letters andpictures, which needs more display elements 10 so that the wiringbecomes more complicated.

The present invention is to provide a technical idea which can avoidsuch complicated wiring.

§1. Fundamental Embodiment of the Present Invention

FIG. 2 is a front view showing the fundamental embodiment to which thepresent invention is applied to the above-described electric bulletinboard. In this electric bulletin board, individual display elements 10(light bulbs) are respectively accommodated within display units 50.Similarly to the electric bulletin board of FIG. 1, the respectivedisplay units 50 are adjacently arranged in a matrix form of five byten, and are housed and fixed within a device casing 90. On the otherhand, an electric power source 60 is provided for the purpose ofgenerating electric power delivered to these respective display units50, and electric power generated at the electric power source 60 isdelivered to the respective display units 50 through an electric powertransmission passage 61.

The important point in this case is that the electric power transmissionpassage is a transmission passage common to the respective display units50. In other words, the electric power transmission passage 61 isconstituted as a single transmission passage to take a routesuccessively including the first display unit 50, the second displayunit 50, the third display unit 50, . . . , the 49-th display unit 50and the 50-th display unit 50. In more practical sense, when two wiringsare drawn into the device casing 90 as the electric power transmissionpassage 61, all wirings are completed. Accordingly, the wiring isextremely simplified as compared to the conventional electric bulletinboard shown in FIG. 1. In addition, even if the number of display units50 is increased for the purpose of improving the resolution, it is stillsufficient to provide two wirings in total.

In order to allow the respective display units 50 to carry out their ownindividual operations while taking such a structure in which electricpower is supplied by the common electric power transmission passage 61,additional components are required to be added to the display elements10 within the respective display units 50. FIG. 3 is a circuit diagramshowing an example of the configuration within one display unit 50. Alight bulb as the display element 10 is connected to the electric powertransmission passage 61 drawn within the device casing 90 so that theelectric power is supplied. In this case, one terminal of the displayelement 10 is connected to the electric power transmission passage 61through a regulator 51. Thus, supply state of the electric power to thedisplay element 10 can be controlled by this regulator 51. In morepractical sense, the regulator 51 is constituted by a relay, and iscapable of carrying out ON/OFF control of power supply to the displayelement 10 (light bulb). Within the display unit 50, a non-volatilememory 52 and a controller 53 are further provided. Display informationfor instructing the display element 10 (light bulb) to change itsdisplay mode in point of time is stored in the non-volatile memory 52.The controller 53 gives instruction to the regulator 51 on the basis ofthis display information to carry out ON/OFF control of the displayelement 10.

FIG. 4 is a Table showing the relationship between an example of displayinformation stored in the non-volatile memory 52 and the state of thelight bulb corresponding to this display information. In this example,one second is defined as a unit time and display information, whichindicates light emitting or non-light emitting (ON/OFF) state for everyunit time by a bit data, is shown at the upper row of the Table. Namely,the display information consists of bit train, and an n-th bit indicatesthe display state after n sec. In more practical sense, a bit “1” isdefined as a bit data indicating light emitting (ON) state and a bit “0”is defined as a bit data indicating non-light emitting (OFF) state. Thelight emitting or non-light emitting (ON/OFF) state of the displayelement 10 (light bulb) is indicated at the lower row of this Table.When reference is made to corresponding portions of both the upper andlower rows, the relevancy between display information prepared and theactual light emitting or non-light emitting (ON/OFF) operations of thelight bulb can be readily understood. The controller 53 sequentiallyreads out such bit train stored in the memory 52 one bit by one bitevery predetermined unit time (1 sec. in this embodiment) to carry outON/OFF control of the regulator 51 on the basis of the bit value thusread out.

In this configuration, since the individual display units 50 areentirely the same in view of hardware, those display units 50 can bemass-produced. If an EEPROM and a processor unit of the clock includedtype are respectively used as the non-volatile memory 52 and thecontroller 53, they can be constituted with elements on one chip. Thus,the structure becomes very simple. In view of software, it is possibleto write inherent display information, such as a data indicated at theupper row of FIG. 4, into the non-volatile memories 52 of the individualdisplay units 50 by using the controllers 53 at the final stage whenthese mass-produced display units 50 are accommodated within the devicecasing 90. Those display units in which the inherent display informationare written can function as an electric bulletin board according to thisinvention. This assembling work is very easy because the wiring step issimplified to much degree. Similarly, maintenance work also becomeseasy.

It is to be noted while, in this embodiment, a data of one bit is usedfor determining the display state per unit time (1 sec. in this example)to carry out simple ON/OFF control, if, e.g., a data of eight bits isused for determining the display state per unit time, a brightnesscontrol with 256 steps of gradation can be also carried out. In thiscase, it is sufficient that a transistor element, etc. is used as theregulator 51 to vary electric current supply to the display element 10with 256 steps.

§2 Embodiment Using Synchronizing Signal

In the above-described fundamental embodiment, fifty light bulbsrespectively independently carry out light emitting or non-lightemitting (ON/OFF) operations. Accordingly, any picture image can bepresented on a display screen constituted by the entirety of the displaydevice shown in FIG. 2. As a matter of course, a picture includingletters (characters) can be also presented. Further, so-called slideshow to switch still pictures every predetermined time can be alsopresented and moving picture can be also presented. In this case, anumber of displaced still pictures or a total display time of the movingpicture is limited by capacity of the memory 52. According as thecapacity of the memory 52 becomes large, a larger number of stillpictures can be presented, and a longer time moving picture display canbe made. The pictures presented are determined by display informationstored in the memories 52 of the respective display units. In otherwords, a user of this display device determines in advance what pictureis to be presented and stores in advance, in the memories 52 of therespective display units, display information (data of bit train in theabove-described example) which is necessary for carrying out suchpresentation.

It is to be noted that in order to present a meaningful picture whenviewed as the entirety of the display device, it is necessary to ensuresynchronization between respective display units. Namely, it isnecessary to synchronize the timings for switching from a display statecorresponding to the n-th bit of the display information indicated atthe upper row of FIG. 4 to the next display state corresponding to the(n+1)th bit of the display information with respect to all the displayunits. If these timings are not in correspondence with each other forthe respective display units, it is impossible to display a correctpicture. Accordingly, it is preferable to deliver a synchronizing signalto the respective display units.

FIG. 5 is a front view showing an embodiment in which means fordelivering synchronizing signal (SYNC signal) is added to theabove-described fundamental embodiment. In this embodiment, centralcontrol device 70 and a signal transmission passage 71 are newlyprovided so that a synchronizing signal generated at the central controlunit 70 is transmitted to the respective display units 50 through thesignal transmission passage 71. FIG. 6 is a circuit diagram showing anexample of the configuration within one display unit 50, wherein thestate where the synchronizing signal on the signal transmission passage71 is taken into the controller 53 is shown. If a clock signalconsisting of, e.g., a rectangular wave is used as the synchronizingsignal, the controllers 53 of the respective display units can switchthe display mode of the display elements 10 at correct timings incorrespondence with the period of this clock signal.

It is true that the central control unit 70 and the signal transmissionpassage 71 are not necessarily required in carrying out this invention.Since it is unnecessary that operation timings of respective displayunits are precisely synchronized in such cases that random abstractpatterns are displayed as a picture image, or in such cases that lightis emitted at random as a simple ornament, it is not required topositively use the synchronizing signal. Moreover, when synchronizationis taken only at the time of start of the display operation using astart timing of power supply as a trigger, synchronization to a certainextent can be ensured even if a perfect synchronization cannot beattained.

However, it is to be noted that, in the case of displaying letters(characters), etc., it is preferable to use the synchronizing signal asfar as possible. From the physical point of view, the electric powertransmission passage 61 and the signal transmission passage 71 shown inFIG. 5 may be constituted by the same conductive wire. For example, ifa.c. power is used as power delivered, the period of this a.c. power canbe utilized as a clock signal. Accordingly, a pair of conductive wiresconstituting the electric power transmission passage 61 perform the roleas the signal transmission passage 71.

§3 Embodiment Using Write Signal

As previously described, the display contents of the electric bulletinboard according to the embodiments mentioned above are determined on thebasis of display information (bit train data) stored in the memories 52within the respective display units. In other words, in these electricbulletin boards, only pictures represented by display information storedin the memories 52 can be displayed. In the case of allowing theelectric bulletin board to display different pictures, displayinformation in the memories 52 must be changed. As a method for carryingout change of display information, there are a first method ofexchanging the entirety of the hardware of the memory 52, and a secondmethod of rewriting the memory content in terms of software. While thefirst method is also actually effective in such a case that the sameadvertisement is repeatedly displayed for a long time, the second methodis practical from a general point of view. In view of the above, theembodiment having a function to rewrite display information in thememory 52 will now be described.

Such a rewrite operation can be carried out by delivering a writesignal, in place of a synchronizing signal, through the signaltransmission passage 71 in the embodiment shown in FIG. 5. In order toallow the display units 50 to respectively carry out individual rewriteprocessing by using single common signal transmission passage 71, it issufficient that addresses are defined with respect to the display units.In the case where fifty display units are disposed as shown in FIG. 5,for example, addresses from the first address up to the fiftieth addressare respectively defined with respect to the display units and theseaddresses are stored in the memories 52 within the respective displayunits. In more practical sense, address information of the “firstaddress” is written in advance in the non-volatile memory 52 within thefirst display unit, and address information of the “fiftieth address” iswritten in advance in the non-volatile memory 52 within the fiftiethdisplay unit.

In this case, the write signal transmitted through the signaltransmission passage 71 is caused to consist of address informationindicating a specific display unit and display information to be newlywritten into the memory 52 within the specific display unit. FIG. 7 is aview showing one example of the format of a write signal as statedabove, wherein a write signal with respect to the specific display unitconsists of “unit data start information” indicating start of the writesignal of one unit, “address information” indicating the specificdisplay unit, “display information” to be newly written, and “unit dataend information” indicating end of the write signal of one unit.

For example, in the case where there is a need to replace former displayinformation stored in the memory within the third display unit with newdisplay information “11001100 . . . ”, it is sufficient to generate awrite signal including data of “address information: the third address,display information: 11001100 . . . ” at the central control device 70to transmit it to all the display units through the signal transmissionpassage 71. The controllers 53 within the respective display units arepreprogrammed to execute the rewrite processing only in the case wherethe own address information assigned to the corresponding controller,which is stored in the memory 52, and address information within thetransmitted write signal are in correspondence with each other. Whensuch a preprogram is made, even if the above-mentioned write signal istransmitted to all the display units 50, only the controller 53 withinthe third display unit 50 in which address information of the “thirdaddress” is written in the memory 52 executes the processing to replacethe display information in the memory 52 by the new display information“11001100 . . . ”. Although the same write signal is transmitted to theother forty-nine display units, the controllers 53 within thoseforty-nine display units do not carry out rewrite processing by anymeans. It is to be noted that, in order to carry out rewrite operationwith respect to plural display units, it is sufficient to repeatedlydeliver a write signal as shown in FIG. 7 with address information beingrespectively changed.

The central control device 70 and the controllers 53 within therespective display units are units including microprocessors, andordinarily have a function to execute various arithmetic processing in atime of the order of microsecond or less than that. Accordingly, theabove-described memory rewrite processing can be executed in such timeof the order of microsecond. On the contrary, it is sufficient that aunit time for changing the display mode of the display element 10 (1sec. in the case of the above-described example) is set to a time tosuch a degree that the naked eye of human being follows change (theorder of millisecond to second). Since the time required for the memoryrewrite processing (the order of microsecond) is very short as comparedto the switching period of the display mode (the order of millisecond tosecond), even if the memory rewrite processing is added, any obstructiondoes not take place in the ordinary switching processing of the displaymode that the controller 53 carries out.

In the device to which such a memory rewrite function is added, thenumber of still pictures to be displayed or the presentation time ofmoving picture to be displayed is not limited by the memory capacity. Ifdisplay information in the memory are sequentially rewritten, it becomespossible to carry out, from a theoretical point of view, presentation ofinfinite number of still pictures or presentation of moving picture ofan infinite time.

It is to be noted that although, in the above-described embodiment, thesame write signal is delivered to all the display units through thesingle common signal transmission passage 71. in the case where arelatively small number of display units are provided, respectivededicated signal transmission passages may be provided for therespective display units. FIG. 8 is a circuit diagram showing anembodiment in which respective dedicated signal transmission passages 72are drawn from the central control device 70 to four display units 50A,50B, 50C, 50D. The four signal transmission passages 72 are respectivelydirectly connected to controllers 53A, 53B, 53C, 53D within the displayunits. In the case where the dedicated signal transmission passages 72are provided as described above, the address information within thewrite signal becomes unnecessary, thus making it possible to deliver thewrite signal at a higher speed.

§4. Embodiment Applied to Color Display

Subsequently, the embodiment in which this invention is applied to thecolor display using light emitting diode will be described. FIG. 9 is acircuit diagram of a display unit 80 having display function of R, G, Bthree primary colors, and FIG. 10 is a partial front view showing theconfiguration of a color display 100 of a structure in which a largenumber of such display units are arranged in a matrix form.

As indicated in the circuit diagram of FIG. 9, three light emittingdiodes 83R, 83G, 83B are included as respective display elements withinone display unit 80. These light emitting diodes are diodes suppliedwith electric power from the electric power transmission passage 61 andrespectively carry out light emitting operations of three primary colorsof red, green and blue. By these three light emitting diodes, colordisplay corresponding to one pixel can be carried out. Power supplieswith respect to the light emitting diodes 83R, 83G, 83B are respectivelycontrolled by regulators 84R, 84G, 84B. The controller 81 givesinstructions to the respective regulators 84R, 84G, 84B on the basis ofdisplay information stored in a non-volatile memory 82. The respectiveregulators control energizing to the respective light emitting diodes onthe basis of these instructions. In this example, the controller 81 issupplied with a synchronizing (SYNC) signal through the signaltransmission passage 71. Thus, changes of the display modes of therespective display units are caused to take place in response to (insynchronism with) the synchronizing signal.

Accordingly, it is necessary to respectively store display informationin the memory 82 for every respective light emitting diodes. If a relayis used as a regulator to carry out simple ON/OFF control, it issufficient to prepare one bit of data for each light emitting diode forindicating the display state during one unit time. If a transistor isused as a regulator to carry out control with brightness changes of,e.g., 256 stages of gradation, it is sufficient to prepare eight bits ofdata for each light emitting diode for indicating the display stateduring one unit time.

As shown in FIG. 10, the respective display units 80 are regular squarewhen viewed from the front, and three light emitting diodes 83R, 83G,83B are accommodated within a unit case 85 functioning as an envelope.Although not shown in FIG. 10, other components shown in the circuitdiagram of FIG. 9 are accommodated as electronic parts within the unitcase 85. On the front of the unit case 85, a light transmissive panel 86is attached. When viewed from the front, the three light emitting diodes83R, 83G, 83B are accommodated behind the light transmissive panel 86.The display units 80 of such a structure are housed in the statearranged in length and breadth directions within the device casing 90.The device casing 90 includes a rectangular frame portion 91 (only oneportion of the left and upper portion thereof is shown in FIG. 10), anda bottom portion (which is not shown in FIG. 10) formed on the bottomsurface thereof so as to cover the inside opening portion of the frameportion 91. A large number of display units 80 are put and arranged onthe bottom portion.

In this example, the color display 100 further includes, although notshown in the figure, electric power source 60, electric powertransmission passage 61 for delivering electric power to the respectivedisplay units 80, central control device 70 and signal transmissionpassage 71 for delivering the synchronizing signal to the respectivedisplay units 80. Of course, a write signal can be delivered through thesignal transmission passage 71, thereby also making it possible torewrite display information in the memory 82. If display information issequentially rewritten, an arbitrary color picture can be displayedsimilarly to the conventional typical color display.

FIG. 11 is a block diagram showing the drive system of a conventionaltypical color display 200. When picture data is written into a picturememory 220 (so called frame buffer) by a CPU 210, a display controller230 delivers a predetermined video signal to the color display 200 so asto carry out picture display corresponding to the picture data. This isthe conventional typical color display drive method. In accordance withthis method, according as the screen size of the color display 200becomes greater, or the resolution of picture on screen becomes higher,the memory capacity required for the picture memory 220 is increased tomore degree. As a result, high access speed is required. In addition,high speed and high grade processing ability is required also for thedisplay controller 230.

On the contrary, in the case where this invention is applied to thecolor display, it becomes unnecessary to provide large capacity picturememory 220 and enhanced function display controller 230. FIG. 12 is ablock diagram showing main components in the case where the displaydevice according to this invention is used to constitute the colordisplay. The major portion of the color display 300 is composed ofplural display units 330. The main components of each display unit 330are a controller 331, a memory 332 and a display element 333. Withineach display unit 330, the controller 331 carries out processing tocontrol display mode of the display element 333 on the basis of displayinformation stored in the memory 332, and is operative so that when awrite signal is given through a signal transmission passage 321 from acentral control device 320. Further, the controller 331 carries outprocessing to rewrite display information in the memory 332 on the basisof the above-mentioned write signal.

The central control device 320 carries out a processing to generate apredetermined write signal on the basis of instruction from a CPU 310 todeliver it to the respective display units 330. As previously described,the transfer time of the write signal between the central control device320 and the respective display units 330 is the order of microsecond andis sufficiently short as compared to the period that the controller 331changes the display mode of the display element 333 (order ofmillisecond to second). Accordingly, even if the rewrite processing withrespect to the memory 332 is added, any obstruction does not take placein the ordinary display processing. Moreover, since the memory 332within each display unit 330 is only required to have a capacitysufficient for only holding display information with respect to the areawhich the own memory is in charge of among the entire picture area as acolor display, there is no necessity for the memory 332 to use a memoryelement with large capacity or high access speed. Similarly, since thecontroller 331 within each display unit 330 is only required to have afunction to merely carry out control with respect to the area which theown controller is in charge of among the entire picture area as thecolor display, a high grade arithmetic processing ability is notrequired as the controller 331. As stated above, according to thisinvention, the burden of the memory 332 and the controller 331 withineach display unit in the color display becomes light to such a degree,because an area which each component is in charge of is reduced ascompared to the picture memory 220 and the display controller 230 in theconventional color display drive system. As a result, those componentscan be constituted with relatively inexpensive electronic parts.

§5. Other Modifications

While this invention has been described in accordance with theillustrated embodiments, this invention is not limited to theseembodiments, but may be carried out in various modes in addition to theabove described mode. Several modifications are indicated below.

(1) While light bulbs or light emitting diodes are used as individualdisplay elements in the above-described embodiments, the displayelements in the fundamental idea. of this invention are not limited onlyto such light emitting elements. For example, there may be employed apanel type display element, etc. having a structure of three-dimensionalbody with plural display surfaces wherein a specific display surface canbe selectively presented at a time by rotating the body by motor, etc.In short, this invention may be applied to any display devices in whicha large number of display elements are arranged on a screen as pixelsand respective display elements have a function to vary their owndisplay mode using electric power drive system to thereby carry outdisplay of information on the screen.

(2) The non-volatile memory and the controller are respectively preparedby EEPROM and microprocessor, etc., in the above-described embodiments.However, any memory having the property to hold storage content alsoafter the power supply is turned OFF may be used as the non-volatilememory. As the controller, if the component having function as describedabove is provided, the wired logic circuit or the transistor circuit maybe used. Further, as the non-volatile memory, not only so calledsemiconductor memory, but also element for mechanically storinginformation, e.g., DIP switch, etc. may be used. In addition, if it isthe premise that rewrite operation of display information is carried outthrough the signal transmission passage, the memory portion in whichdisplay information is stored may be constituted with volatile memorysuch as RAM, etc.

(3) As previously described, the electric power transmission passage 61and the signal transmission passage 71 may be caused to be commonly usedto transmit electric power and display signal in the superimposed stateby way of physically the same conductive wire. Moreover, it is notnecessarily required to use physical conductive wire for transmittingelectric power or display signal to respective display units. Forexample, supply of electric power or display signal may be also carriedout by magnetic coupling, and display signal may be also delivered torespective display units by utilizing radio or light (e.g., infraredray). Particularly, if optical fiber is used as the signal transmissionpassage 71, it becomes possible to transmit the write signal at a highspeed. In addition to this, even if the number of display units isincreased, drawback such as voltage drop, etc. does not take place.

(4) While one pixel is constituted by a single display unit in theabove-described embodiments, a plurality of display elementscorresponding to plural pixels may be included within a single displayunit. While, in the embodiment shown in FIG. 10, for example, threelight emitting diodes 83R, 83G, 83B are included within a single displayunit 80 to carry out display of one pixel by these three light emittingdiodes, e.g., a group in which these display units 80 are arranged in amatrix form of four rows by four columns may be handled as a singledisplay unit. In this case, sixteen sets of pixel component eachcomprised of three light emitting diodes are provided within the singledisplay unit so that forty-eight light emitting diodes in total andforty-eight regulators in total are included therewithin. In such aconfiguration, it is still sufficient to provide single memory andsingle controller for the single display unit, since display informationwith respect to respective forty-eight light emitting diodes can bestored into the single memory.

(5) While, in the above-described embodiments, the controller withineach display unit executes a processing determined in advance (displayprocessing to control respective regulators on the basis of displayinformation in the memory and processing to rewrite display informationin the memory when the write signal is given), if a design is made suchthat the controller executes these processing by making reference to apredetermined control program stored in the memory, an approach may beemployed to rewrite the control program in the memory to therebysuitably change the processing content of the controller.

For example, in the circuit diagram shown in FIG. 6, it is sufficient tostore, in advance, both the display information and the control programin the memory 52 within the display unit 50. The controller 53 executesthe control program stored in the memory 52 to thereby execute displayprocessing to control the regulator 51 and processing to rewrite thedisplay information in the memory 52 on the basis of the write signaldelivered from the signal transmission passage 71. If a given writesignal includes an instruction for rewriting display information, arewrite operation of the display information in the memory 52 isexecuted and the display mode of the display element 10 is changed ashas been described in the aforesaid embodiments. On the other hand, if agiven write signal includes an instruction for rewriting controlprogram, a rewrite operation of the control program in the memory 52 isexecuted and the processing operation itself of the controller 53 can bechanged.

Of course, by giving a write signal with a respective address in thecase of carrying out rewrite operation of the control program, differentrewrite operations of control programs for respective display units canbe carried out, even if a common signal transmission passage is used.

(6) As the controller within each display unit, any device having afunction capable of controlling the regulator on the basis of displayinformation in the memory may be used. For example, the controller maybe constituted by a gate array or a PLA element. It is to be noted thatif a device having arithmetic processing function is used as acontroller, data within the write signal delivered through the signaltransmission passage 71 can be transmitted in the compressed state. Forexample, in the case of transmitting a write signal as shown in FIG. 7from the central control device 70, data of the portion of the displayinformation can be compressed in advance. In the case where such atransmission of compressed data is carried out, the controller 53 shownin FIG. 6 receives display information in the compressed state. In thisinstance, if processing program for expanding the compressed data isincluded in advance (or is stored in the memory 52), the receivedcompressed data may be expanded to store it into the memory 52.Alternatively, such an approach may be employed that the controller 53stores display information into the memory 52 in the compressed statewhen it received and it expands the stored compressed data when it readsout every time to carry out the actual display. Such a data compressionis effective particularly in the case of presenting moving picture.

Further, data may be changed to coded data. For example, let considerthe case where sixty-four light bulbs arranged in eight by eight matrixare included as display elements within one display unit. Then a hundredof such display units are arranged in ten by ten matrix to constitute anelectric bulletin board. In this case, one letter (character) ofalphabetic figure consisting of eight by eight dots can be displayed byone display unit. Thus, display of a hundred letters (characters) can bemade as the entirety of the electric bulletin board. On the other hand,display information with respect to sixty-four light bulbs arerespectively stored in the memories within the display units. In such acase, bit map data of specific letters (characters) consisting ofsixty-four bits (data designating light emitting or non-light emittingstate with respect to respective sixty-four light bulbs) are stored intothe memory as display information. In place of this, ASCII code, etc. ofa specific letter (character) can be also stored as display information.Since the controller 53 has the arithmetic processing function, it issufficient to carry out decoding work for expanding bit map data of aneight by eight matrix on the basis of the ASCII code which has been readout from the memory 52. If coded data is used in place of actual picturedata (bit map data) as described above, data capacity of the writesignal delivered through the signal transmission passage from thecentral control device can be reduced.

Moreover, function to carry out thinning processing or interpolationprocessing between or with respect to pixels may be added to thecontrollers within respective display units. This is effective in thecase where a resolution of pixel arrangements of plural display elementsin the display unit and a resolution of display information stored inthe memory are not in correspondence with each other. For example, letconsider the case where sixty-four light bulbs arranged in eight byeight matrix are included as display elements within one display unit.There is no problem in the case where display information in the memoryis picture information similarly having the resolution of eight byeight. However, in the case where that display information is pictureinformation having resolution of sixteen by sixteen, it is sufficient toexecute thinning processing of pixels at the controller to reduce theresolution so that eight by eight is provided. In contrast, in the casewhere display information in the memory is picture information havingresolution of four by four, it is sufficient to execute interpolationprocessing of pixels at the controller to increase the resolution sothat eight by eight is provided.

In addition, not only the above-described spatial thinning processing orinterpolation processing, but also the thinning processing or theinterpolation processing in point of time can be carried out. Forexample, in the case where display information in the memory is movingpicture information which varies the display state every 1 sec, anapproach may be employed at the controller to thin such moving pictureinformation into ½ to vary the display state every 2 sec, or to carryout interpolation in a manner opposite to the above to generate anintermediate display state to vary the display state every 0.5 sec.

Industrial Applicability

A display device according to this invention can be widely utilized forelectric bulletin boards or large display devices in which a largenumber of light bulbs, light emitting diodes or rotational panels arearranged. Particularly, this display device can be utilized as a displayfor advertising propaganda in the place where people are gathered suchas station or plaza, etc. Such a utilization form to repeatedly presenta moving picture of several minutes can be made. In addition, if thedisplay device itself of this invention is utilized as a part ofarchitecture such as a wall, etc., the architecture can provide anintelligent illuminating function.

What is claimed is:
 1. A display device comprising: an array of displayunits; display elements respectively in the display units forlight-emitting operation; memories respectively in the display units forstoring variable display sequence information that designates thelight-emitting operation of the respective display elements; andcontrollers respectively in the display units for determining thelight-emitting operation of the respective display elements on the basisof the display sequence information that designates the light-emittingoperation of the respective display elements so that the displayelements carry out the light-emitting operation designated by theirrespectively associated memories.
 2. The display device as set forth inclaim 1: wherein at least one of the display elements is a first colorpresentation element (83R) for presenting a first primary color, asecond color presentation element (83G) for presenting a second primarycolor and a third color presentation element (83B) for presenting athird primary color.
 3. The display device as set forth in claim 1, andfurther comprising: a control device (70; 320) for generating asynchronizing signal; and signal transmission means (71; 321) fordelivering the synchronizing signal to the controllers; wherein thecontrollers determine the emitting from a time synchronized with thesynchronizing signal delivered thereto.
 4. The display device as setforth in claim 1, and further comprising: a control device (70; 320) forgenerating a write signal; and signal transmission means (71; 321) fordelivering the write signal to the memories to rewrite the displaysequence information thereof on the basis of the write signal deliveredthereto.
 5. The display device as set forth in claim 4: wherein firstaddresses for the respective display units are stored in the respectivememories; and wherein the write signal comprises second addresses torewrite the display sequence information of the memories when the firstand second addresses correspond.
 6. The display device as set forth inclaim 1, and further comprising: a device (70; 320) for generating awrite signal; and signal transmission means (71; 321) for delivering thewrite signal to the memories; wherein the memories store further displaysequence information and substitute the further display sequenceinformation for the display sequence information on the basis of thewrite signal delivered thereto.
 7. The display device as set forth inclaim 6: wherein first addresses for the respective display units arestored in the respective memories; and wherein the write signalcomprises second addresses to substitute the further display sequenceinformation when the first and second addresses correspond.
 8. Thedisplay device as set forth in claim 3: wherein the signal transmissionmeans also supplies electric power to the display units.
 9. The displaydevice as set forth in claim 4: wherein the write signal is compressedor encoded in the control device and expanded or decoded within thecontroller.
 10. The display device as set forth in claim 4: wherein thecontrollers carry out thinning processing or interpolation processingwith respect to the display sequence information stored in therespective memories.
 11. The display device as set forth in claim 2, andfurther comprising: a control device (70; 320) for generating asynchronizing signal; and signal transmission means (71; 321) fordelivering the synchronizing signal to the controllers; wherein thecontrollers determine the emitting from a time synchronized with thesynchronizing signal delivered thereto.
 12. The display device as setforth in claim 2, and further comprising: a control device (70; 320) forgenerating a write signal; and signal transmission means (71; 321) fordelivering the write signal to the memories to rewrite the displaysequence information thereof on the basis of the write signal deliveredthereto.
 13. The display device as set forth in claim 3, and furthercomprising: a control device (70; 320) for generating a write signal;and signal transmission means (71; 321) for delivering the write signalto the memories to rewrite the display sequence information thereof onthe basis of the write signal delivered thereto.
 14. The display deviceas set forth in claim 11, and further comprising: a control device (70;320) for generating a write signal; and signal transmission means (71;321) for delivering the write signal to the memories to rewrite thedisplay sequence information thereof on the basis of the write signaldelivered thereto.
 15. The display device as set forth in claim 13:wherein first addresses for the respective display units are stored inthe respective memories; and wherein the write signal comprises secondaddresses to rewrite the display sequence information of the memorieswhen the first and second addresses correspond.
 16. The display deviceas set forth in claim 2, and further comprising: a device (70; 320) forgenerating a write signal; and signal transmission means (71; 321) fordelivering the write signal to the memories; wherein the memories storefurther display sequence information and substitute the further displaysequence information for the display sequence information on the basisof the write signal delivered thereto.
 17. The display device as setforth in claim 13: wherein the signal transmission means also supplieselectric power to the display units.
 18. The display device as set forthin claim 6: wherein the write signal is compressed or encoded in thecontrol device and expanded or decoded within the controller.
 19. Thedisplay device as set forth in claim 6: wherein the controllers carryout thinning processing or interpolation processing with respect to thedisplay sequence information stored in the respective memories.
 20. Thedisplay device as set forth in claim 7: wherein the controllers carryout thinning processing or interpolation processing with respect to thedisplay sequence information stored in the respective memories.
 21. Adisplay device comprising: an array of display units, each of thedisplay units comprising: a display element for light-emittingoperation; a memory for storing predetermined particular displaysequence information that designates the light-emitting operation of thedisplay element; and a controller for determining the light-emittingoperation of the display element on the basis of said predeterminedparticular display sequence information stored in the memory so that thedisplay element carries out the light-emitting operation.
 22. Method foroperating a display device comprising steps of: a first step ofpreparing a display device comprising an array of display units, each ofthe display units comprising a display element for light-emittingoperation, a non-volatile memory for storing data and a controller forcontrolling the display element based on data in the non-volatilememory; a second step of preparing inherent display sequence informationdesignating light-emitting operation for the respective display elementsand storing said inherent display sequence information to thecorresponding non-volatile memory as data; and a third step offunctioning the respective controllers so that the respective displayelements carry out the light-emitting operation based on data stored insaid second step in the corresponding non-volatile memories; whereinsaid second step is carried out in advance before said third step iscarried out.
 23. A display device comprising: an array of display units,each of the display units comprising: a display element forlight-emitting operation; a memory for storing variable display sequenceinformation that designates the light-emitting operation of the displayelement; and a controller for determining the light-emitting operationof the display element on the basis of the display sequence informationthat designates the light-emitting operation of the display element sothat the display element carries out the light-emitting operationdesignated by the memory.